Bitmap-only font scaling?

Issue description

If I modify samplecode/SampleText.cpp to load a bitmap-only font, I expect that Skia do the bitmap scaling for me transparently. But it doesn't. If I ask for font sizes other than the bitmap strikes, I get nothing rendered. This is with the FreeType font host.

I locally modified the 'typefacerendering' gm to use my local 10x20.pcf.gz , and everything works more or less as expected. Scaling, rotation, subpixel positioning and mask effects (blur) all work fine. If building with SK_USE_FREETYPE_EMBOLDEN then fake bold also works. Path effects are ignored, and it appears hairline stroking won't work. There is currently one issue in testing when FreeType thinks there is an actual outline or not, but that's issue 7878 which I think I know how to fix now.